if else

if else:

guess_age = int(input("please input a age:"))

age = 59   #变量名不能以空格开头

#if else 直接用:冒号来区分，相对来说比较简单
if age == guess_age:

   print("you got the right age")
else:

   print("sorry,you are wrong")

特殊：l连比运算符----------------------------------
#if elfi: else: 
if age == guess_age:

   print("you are right")
elif age > guess_age:
   print("you need a big one")
else:
   print("you need a small one")

a = 100
b = 1000

c = int(input("input a number:"))

if  a <= c <= b :

   print(" it's true")
else: 
   print ("flase")

input---------------------------------------------------------------

name = input ("your name:")

age = input ("your age:")
#input 所接收到的，所有输入的，都会被识别为字符串，即使输入的是数字

old = 100
#这里用了两种拼接方式，一种是用逗号，另一种是用加号（同一类型的相关拼接好，字符串和字符串之间，或是数字和数字之间。）
print(name,"you can still live",old + int(age),"years")#逗号空格
print(name,"you cat still to live " + str(old + int(age))+ " years")#加号没空格